1. Field of the Invention
The present invention relates to automatic travelling apparatus in which a vehicle determines a path to follow on road.
2. Description of the Prior Art
A conventional automatic travelling system uses an image pickup device attached to a vehicle to steer the vehicle, thereby permitting it to follow a guide line which is laid on the road (See Japanese Patent Publication No. 58-42482 and Japanese Patent Application Public Disclosure No. 62-140109).
Apparently, such an automatic travelling system is useless on the road having no guide line.
Another example of automatic travelling system is an automatic power lawn mower equipped with an image pickup device such as a video camera. While continuously taking images of the lawn area ahead of the mower, these images are treated to enhance the difference of shade between the finished and unfinished areas, thereby permitting exact detection of the boundary between the finished and unfinished areas. The mower is steered to travel along the boundary thus detected (See Japanese Patent Application Public Disclosure No. 62-70916).
This automatic travelling system is capable of determining a course to follow, but this automatic travelling system is essentially the same as the first automatic travelling system described above in respect of that the vehicle follows a single guide line on the road.
When a vehicle is running on the road, an appropriate path to follow on the road should be determined by taking the width of the road and the running speed of the vehicle into consideration.